The goal of the research proposed is to develop and evaluate nontransformed ductal cell cultures of rat parotid glands to be used as models for the in vitro study of the physiological and pathophysiological changes that occur in exocrine gland cells. The objective will be the long-term culture of ductal cells and the passaging of these cells, thereby making cells available for study over a longer period than an acute experiment. Because cells tend to dedifferentiate in culture, ductal cells will be isolated from dispersed cell preparations prior to culturing while the cells still have their characteristic morphology. Ductal cells will be isolated and analyzed biochemically to obtain baseline data. The rat parotid gland has been chosen for these studies because the majority of the ducts are striated (Redman, 1987; Robinovitch, 1967) and striated ducts are important in regulation of electrolytes (Schneyer et al., 1972). Isolated ductal cells will be grown in basement membrane coated culture dishes. The resulting cultures will be morphologically and biochemically characterized. To insure that the cells in culture are ductal in origin, antibodies to ductal cell markers will be used.